A beanie is a soft, snug-fitting cap that covers your head and sometimes your ears, keeping you warm in cold weather. Unlike a baseball cap with its stiff brim, a beanie is made from stretchy knitted fabric that hugs the shape of your head. Picture a sock for your head (but much more stylish!).

Beanies became popular in the early 1900s when workers wore them to keep warm in factories and on construction sites. Today, people wear beanies while skiing, playing outside in winter, or just walking to school on a chilly morning. Some beanies have a fluffy pom-pom on top, while others are plain and simple.

You might also hear people call them knit caps or stocking caps. In some places, people wear beanies year-round as a fashion choice, not just for warmth. When you pull a beanie down over your ears on a freezing day, you'll understand why this simple invention has stayed popular for over a century.